Muscles of the Head and Neck

Question 1

What is the name, origin, insertion, innervation, and action of this muscle.

Answer 1

Name: Sternocleidomastoid

Origin: Manubrium of sternum & medial portion of clavicle

Insertion: Mastoid process of temporal bone & superior nuchal line of occipital bone

Innervation: Accessory nerve

Action: (1) prime mover of active head flexion (when act together) & (2) rotates head toward opposite side (when act singularly)

Question 2

What is the name, origin, insertion, innervation, and action of this muscle.

Answer 2

Name: Trapezius

Origin: Occipital bone, ligamentum nuchae, spines of C7 - T12

Insertion: spine & acromion of scpaula, lateral 3rd of clavicle.

Innervation: Accessory nerve

Action: (1) rotates scapula, (2) adducts and retracts scapula, (3) elevates and depresses scapula

Question 3

What is the name, origin, insertion, innervation, and action of this muscle.

Answer 3

Name: Temporalis

Origin: Temporal fossa

Insertion: coronoid process of mandible

Innervation: Trigeminal nerve

Action: (1) closes jaw, (2) elevates and retracts mandible, (3) synergist of pterygoids, and (4) maintains position of mandible at rest

Question 4

What is the name, origin, insertion, innervation, and action of this muscle.

Answer 4

Name: Masseter

Origin: Zygomatic arch and maxilla

Insertion: angle & ramus of mandible

Innervation: Trigeminal nerve

Action: (1) prime mover of jaw closure and (2) elevates mandible

Question 5

What is the name, origin, insertion, innervation, and action of this muscle.

Answer 5

Name: Buccinator

Origin: Molar region of maxilla and mandible

Insertion: Orbicularis oris

Innervation: Facial nerve

Action: (1) draws corner of mouth laterally, (2) compresses cheek (sucking), and (3) holds food between teeth during chewing.